Tate was born in Bloomsbury and brought up in the Brunswick Centre.[2] Her mother, Josephine, was a florist,[5] and Tate has said that the character of Margaret in The Catherine Tate Show, who shrieks at the slightest of disturbances, is based largely on Josephine.[2]

Tate never knew her father as he left very early on in her life[2] and, consequently, she was brought up in a female-dominated environment, being cared for by her mother, grandmother and her godparents.[5] As a child, Tate suffered from an obsessive-compulsive disorder which centred on word association. For example, Tate was not able to leave a jumper on the floor or it might have brought misfortune to her mother whose name began with the letter "J" like jumper.[2]

Tate was approached at a post-show party at the Edinburgh Festival by then-BBC controller of comedy Geoffrey Perkins, who encouraged Tate to develop her character ideas, especially to push the boundaries with teenager Lauren Cooper. Undertaking Perkins' advice, after a live show Tate found the audience walking out of the show repeating the character's catchphraseAm I bovvered?[12]

Produced by Perkins at Tiger Aspect, Tate was given her own programme on BBC Two in 2004, which she co-wrote and starred in with Derren Litten, entitled The Catherine Tate Show, which ran for three series.[9] Two of the show's well-known characters are teenager Lauren Cooper and Joannie "Nan" Taylor, the cockney grandmother.[7] Tate's inspiration for the cockney grandmother came from visits to old people's homes when she was at drama college.[7] Tate won a British Comedy Award for Best Comedy Newcomer for her work on the first series of The Catherine Tate Show,[13] and with the first series becoming a success, in March 2005, Tate made a guest appearance during the BBC's Comic Relief as the character of Lauren from The Catherine Tate Show, alongside boy-band McFly, which gained her further exposure.[8]

In November 2005, Tate appeared in another charity sketch as part of the BBC's annual Children in Need telethon. The segment was a crossover between EastEnders and The Catherine Tate Show, featuring Eastenders characters Peggy Mitchell, Little Mo Mitchell and Stacey Slater, whilst Tate appeared as Lauren.[14] Also at that time, she was a guest star at the 77th Royal Variety Performance and appeared again in the guise of Lauren Cooper. During the sketch, Tate looked up at the Royal Box and asked The Queen, "Is one bovvered? Is one's face bovvered?".[15] During the sketch, co-star Niky Wardley (in character as Liese) remarked: "That old man sitting next to her has fallen asleep." Prince Philip then reportedly complained to the show's executive producer, saying he had been insulted.[2] Tate later won a British Comedy Award for Best British Comedy Actress for her work in the second series of The Catherine Tate Show.[16] At the end of 2005, she appeared in the BBC television adaptation of Bleak House.[17]

Tate returned to the stage for the first time since working with the RSC,[18] to play a role in the 2005 West End revival of Some Girl(s), alongside Sara Powell, Lesley Manville, Saffron Burrows and Friends star David Schwimmer.[19] In an interview, Tate commented that she could not look Schwimmer in the eye during her time with him, leading to speculation that the pair did not get on.[6] Tate immediately denied the rumours, explaining that she was joking about her attempts to act "cool" around Schwimmer, whom she described as "a very funny, personable man, and easy to get along with".[20]

The third series of The Catherine Tate Show aired in 2006, going on to win the National Television Award for most popular comedy as voted for by the public,[21] and Tate's catchphrase "bovvered", used by her character Lauren Cooper, became so influential in popular culture that it was named Word of the Year and was even poised to enter the Oxford English Dictionary.[22] Tate also played the role of Donna Noble in Doctor Who, a woman in a wedding dress who suddenly appears in the TARDIS at the end of the episode "Doomsday".[23] The following episode, the Christmas special entitled "The Runaway Bride", saw Tate's character in a major role, where she was temporarily the Doctor's companion.[23] On her appearance in the series, Tate commented "I'm honoured and delighted to be joining David Tennant aboard the TARDIS. I was holding out for a summer season at Wiganrep but as a summer job, this'll do."[24]

Despite speculation that the third series of The Catherine Tate Show would be the last, Tate and the BBC have not ruled out further episodes.[18] She later filmed a one-off special episode which aired on Christmas Day 2007.[30] The episode was subject to criticism when 42 viewers complained about the amount of swearing, and accused Tate of bigotry over the depiction of a family from Northern Ireland as terrorists, whose Christmas presents included a balaclava and a pair of knuckle dusters, in reference to the Troubles.[31] After the complaints were made, an Ofcom report later concluded that the show was not offensive and did not violate broadcasting regulations.[32][33] An extract from the Ofcom report read "Overall this episode was typical of the Catherine Tate Show and would not have gone beyond the expectations of its usual audience. For those not familiar with the show, the information given at the start was adequate."[34]

She has also been nominated for four BAFTA Awards for her work on The Catherine Tate Show to date, including Best Comedy Performance.[35]

Tate returned to Doctor Who in 2008 to reprise the role of Donna Noble as the Doctor's companion throughout the fourth series, which was shown on BBC One starting on 5 April for a 13-week run.[36] Producer Russell T Davies said, "We are delighted that one of Britain's greatest talents has agreed to join us for the fourth series." Tate added, "I am delighted to be returning to Doctor Who. I had a blast last Christmas and look forward to travelling again through time and space with that nice man from Gallifrey."[3] At the TV Quick Awards 2008, Tate was voted best actress for her role in Doctor Who.[37] She returned as Donna Noble in the two-part Doctor Who Christmas special "The End of Time" which was broadcast over Christmas 2009.[38][39]

Tate suffered from post-natal depression,[5] from which she only recovered after the filming of the second series of The Catherine Tate Show.[2] She also suffers from occasional panic attacks.[2] Regarding her personal outlook, Tate has said "I'm an incredibly negative person, so any form of success is only ever going to be a relief to me and set my default position back to neutral."[5]